The return value has no specified semantics. It is an opaque pointer. One typical use case for it is to return a pointer to a table of function pointers. These function pointers can then be used to access the handle's functionality (see the example).

Pointers returned by hquery are meant to be cachable. In other words, if you call hquery on the same handle with the same type multiple times, the result should be the same.

h: The handle.

RETURN VALUE

In case of success the function returns opaque pointer. In case of error it returns NULL and sets errno to one of the values below.